1. Field of the Invention
The present invention relates, in general, to watthour meters and meter sockets and, more specifically, to watthour meter socket adapters.
2. Description of the Art
In the electric utility industry, plug-in, socket-type watthour meters are commonly used to measure electric power consumption at residential or commercial sites. A socket housing is mounted on a convenient wall of the residence or commercial building and contains pairs of line and load terminals which are respectively connected to electric line and load conductors. The terminals receive blade contacts on a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals.
Plug-in socket adapters and socket adapters/extenders, both hereafter referred to simply as socket adapters, are designed to plug into the meter socket housing terminals. Such socket adapters are employed to convert ringless style sockets to ring style sockets or to extend the mounting position of the jaw terminals in the socket housing outward from the socket housing for mounting various electrical equipment, such as test devices or survey recorders, in the socket housing.
Such socket adapters employ a generally annular base having a shell joined thereto and extending outward from one side of the base. Contacts are mounted in the shell and base. Each contact has a female jaw portion disposed interiorly within the shell and a male blade terminal connected to the female jaw portion and extending outward from the shell and the base for a plug-in connection to the terminals in the meter socket housing.
Such socket adapters may be employed in both ring style and ringless style socket housings. In a ring style housing, a raised mounting flange is formed on the front cover of the socket housing to which the peripheral edge of the base of the socket adapter mates and is locked thereto by means of a conventional, annular, lockable sealing ring. In a ringless style socket housing, the peripheral edge flange of the base of the socket adapter is disposed interiorly within the socket housing in close proximity to or engagement with a raised annular portion of the cover surrounding an aperture through which the shell portion of the socket adapter extends. In both ringless and ring style socket housings, a separate sealing ring is mounted about an end mounting flange at the outer end of the shell to lockably mount a watthour meter to the socket adapter.
In previous watthour meter socket adapters, the jaw contacts were of two different constructions. In one construction, the jaw contacts have a folded over design formed of a base wall which is fixedly mounted to the shell of the socket adapter and two spaced side walls extending therefrom. The outer ends of the side walls are folded over inwardly between the side walls and terminate in parallel end flanges which slidably receive a blade terminal of a watthour meter.
In the second construction, the jaw contacts are formed of a generally planar terminal having opposed first and second ends. An angularly bent spring clip is riveted at one end to an intermediate portion of the terminal and extends to a contact edge disposed in separable engagement with the first end of the terminal to form a jaw for receiving the blade terminal of a watthour meter. The spring clip forcibly biases the watthour meter terminal into secure electrical engagement with the terminal. The second end of the blade terminal extends exteriorly from the base of the watthour meter socket adapter for releasable engagement in a socket jaw contact. A cotter pin is inserted through an intermediate aperture in the terminal to fixedly mount the terminal and jaw contact in position in the watthour meter socket adapter.
In both types of jaw contact constructions, the jaw contact presents a constant width surface to the insertion of a watthour meter blade terminal there passed. This requires a high insertion point to separate the contact edges of the jaw contact to enable the blade terminal to slide there-between.
In both bottom connected A to S type adapters as well as S-type socket extenders/adapters, a surge ground conductor is mounted on the meter mounting flange of the socket adapter to engage a ground tab on the base of the watthour meter when the watthour meter is coupled to the socket adapter. A separate wire conductor is connected to the surge ground conductor and passes through the base of the socket adapter to a ground connection in the meter socket. In other types of socket adapters, a rigid connector strap is connected to the surge ground conductor mounted on the meter mounting flange and extends to the base of the socket adapter where it is connected to the base of the socket adapter by a metal fastener. The fastener extends through the base of the socket adapter housing and serves as a mount for a metal tab. The metal tab is positioned exteriorly of the base of the socket adapter housing as in an S-type meter base and engages a corresponding ground contact or connection in the meter socket when the socket adapter is mounted in the meter socket.
In another arrangement of the surge ground conductor, disclosed in pending U.S. patent application Ser. No. 08/611,933, which is assigned to the Assignee of the present application, the surge ground conductor is formed with a first conductive portion of generally annular shape which is disposed in registry with the annular side wall of the socket adapter housing. At least one and, preferably, a pair of tabs extend angularly outward from one end of the first conductive portion and seat in notches formed in the mounting flange of the socket adapter housing. The top and/or bottom surfaces of the tabs are exposed to the mounting flange to enable contact between the tabs and a sealing ring and/or ground tab on a watthour meter when a watthour meter and a sealing ring are mounted on the socket adapter mounting flange. The first conductive portion is fixedly mounted on the sidewall of the shell by means of a mechanical fastener, such as a screw, which is also used to connect a second conductive member or strap to a ground connection externally of the socket adapter housing.
While the above described construction of a watthour meter socket adapter provides an effective socket adapter which fully meets all of its design and application requirements, the watthour meter socket adapter assembly process involves many steps which add to the overall cost of the socket adapter. For example, the base and shell are formed of two separate members which must be joined together by mechanical fasteners. Further, the jaw contacts in the socket adapter are mechanically mounted to the socket adapter housing by means of screws, cotter pins, etc.
Thus, it would be desirable to provide a watthour meter socket adapter which has a simplified construction for ease of manufacture with less separate manufacturing steps or operations. It would also be desirable to provide a watthour meter socket adapter which can be assembled with a minimal number of mechanical fasteners for a reduced cost and ease of manufacture. It would also be desirable to provide a watthour meter socket adapter having a mounting flange adaptable for mounting in ringless style watthour meter socket covers having varying diameter openings. It would also be desirable to provide a watthour meter socket adapter having a unique jaw contact construction which reduces the insertion force required to insert a blade terminal into the jaw contact; while still maintaining the high pull out force of the jaw contact.